1-Hydroxypyrene is a metabolite of the noncarcinogen pyrene found in urine that is always a component of PAH mixtures. 1-hydroxypyrene is an accepted biomarker of carcinogenic Polycyclic aromatic hydrocarbons (PAH) dose(PMID: 15159317 ). PAH are a diverse group of environmental carcinogens formed during the incomplete combustion of organic matter. PAHs are believed to play an important role as causes of human cancer, particularly in certain occupational settings and in cigarette smokers. (PMID: 15247141 ).